Adjustable capillary leak



,lune 24, 1947. A, c. MER r M. 2,422,921

ADJUSTABLE CAPILLARY LEAK Filed July 6, 1944 `Patented June 24, Y

ADJSTABLE CAPILLABY LEAK Alfred 0. C. Nier, New York, N. Y., Edward P.

Ney, Charlottesville, Va., and Mark G. Inghram,

' New York, N. Y., assignors tothe United States o! America, represented by the Director of the Office of Scientific Research and Development Application July 6, 1944, Serial No. 543,699

1i claims.

This invention relates generally to la device for controlling the ilow of small quantities of' fluid and, more particularly, to an adjustable capillary leak for gases or vapors. A

One of the applications of a device of this character is in the control of the gasA being fed into a mass spectrometer. The amounts.of gas used in analysis ofgas in a mass spectrometer are small in volume and are fed to the mass spectrometer in an attenuated flow. Ordinary means of controlling such a stream are insensitivel complicated and inadequate. r

When regulating the flow of small quantities of gas, as attenuated and at as low a pressure as in this case. a conventional valve acting to reduce the stream atone point vin a supply line is too coarse of adjustment for easy and elcient operation. What we have discovered is that the flow of attenuated gases at low pressures can be accurately controlled by varying the frictional resistance to the ilow in abortion of tubing forming a part of the supply line and thus varyingthe loss of head, and, consequently, the rate of iiow.

The quantity of gas flowing through the tubing is determined by the pressure or head on the gas and the frictional resistance within the pipes and tubing.v If the resistance to the ilow of the gas is increased and the pressure remains the same, the mass flow of gas past a given point is accordingly reduced.

It is therefore, an object of this invention to provide an improved means for controllably feeding fluid in small quantities.

It is another object of this invention to provide means for governing the ilow of an atten-uated stream of uid through capillary tubing.

It is a further object to provide readily controlled means for producing slight changes in the flow of small quantities of gas or vapor.

This invention has as another object to provide means for regulating the flow of a gas or vapor by increasing and decreasing the size of the aperture made by the passage within the tubing.

It is a still further and specific object to provide an adjustable capillary leak for regulating the flow of gas to a mass spectrometer.

In the embodiment to be disclosed in detail, the adjustable capillary leak of this invention comprises a rotatable shaft on which a flattened 'tubing is wound spiraliy around and fastened to the shaft so that rotation of the shaft either increases or decreases the size of capillary passages in the tubing, and suitable means for rotating the shaft to make and maintain such an adjustment.

The foregoing and other features of this invention contributing toits simplicity of construction and dependability in operation will be apparent from the following detailed description o! a preferred embodiment taken with the accompanying drawings. in which:

Fig. 1 is a top plan view of the adjustable capillary leak;

Fig. 2 is an enlarged perspective view of a s ection of the flattened capillary tubing; f

Fig. 3 is a plan view of a bent section of the capillary tubing showing the manner of fastening it to the shaft and Fig. 4 is a front view ofthe adjustable capillary leak.

With reference to Fig. 1, a shaft Ils mounted in a frame 2 and is conveniently rotatable in spaced journal openings 3, 3 in frame 2 by means of a worm wheel 4 and an interengaging worm 5 turned by a spindle t. Spindle B is manually operable and has a knurled knob 1 at its end for the purpose. A tubing l of corrosion resisting material is formed from a piece of tubing, preferably copper, of from one-eighth of an inch to one-quarter of an inch in outer diameter and one to two feet in length. 'I'he center portion of the tubing 8 is flattened until the walls collapse, leaving narrow passages I'I between the contiguous or nearly contiguous inner walls 9. as shown in Fig. 2, through which an attenuated flow of gas or uid may be passed. 'I'he center of the flattened portion of tubing 8 is then bent into approximately U-shape and the apex of the bend is brazed, soldered or otherwise suitably secured to the shaft I at a point III. as shown in Fig. 3. The two arms II and I2 of tubing 8 are spirally wound around shaft I (three-sixteenths of an inch in diameter) in opposite directions from the point I0. That is to say, as viewed in Fig. 1, the coiled arm II is wound around the shaft I to form a left-handed helix I3, and the coiled arm I2 is wound around the shaft to form a right-handed helix I4. Fig. 4 shows the ends of the two arms II and I2 extending from the shaft I and rigidly held in frame 2 by opposed clamping members I5, I5 tightened by screws I6, I6, thereby fixing the arms II and I2 to a relatively stationary object.

Arm II is intended to be connected to the supply of gas, vapor, or other fluid that is to pass through the leak, and arm I2 is intended to be connected to the closed system of a mass spectrometer or other device into which the gas or other fluid is being fed. Shaft I is fastened in the relatively stationary member or frame 2 so as to be freely rotatable either clockwise or counter-clockwise in the journal openings 3, 3. 'I'ub-l ing 8, anchored in the frame 2 by clamping members I5, I and fastened to the rotatable shaft I at point I0, and being of flexible material, will permit the coil to loosen or tighten upon relative rotation of shaft I and frame 2.

The counter-clockwise rotation of shaft I as viewed from the right side of Fig. 1 causes the helixes I3 and I4 to tighten, decreasing the radius of curvature thereof and causing tubing 8 to be drawn flatter. 'I'his flattening of the tubing causes a decrease in the size of the narrow passages I1 in the flattened portion of the tubing 8, with a consequent increase in resistance to the flow of fluid therethrough. Conversely, clockwise rotation of the shaft I loosens helixes I3 and I4 and increases the size of the narrow passages Il, consequently decreasing the resistance to the flow oi iluid. Therefore, tightening of the helixes I3 and I4 increases the resistance to the flow of fluid through the tubing 8 and loosening the helixes I3 andV I4 decreases the resistance to the flow of fluid through the tubing 8. 'I'hese results are obtained because the tightening of the helixes I3 and I4 causes the clearances between the inner walls 9 of tubing 8, deflning the passages therethrough, to become more constricted. By increasing and decreasing the resistance to the ilow of fluid the mass flow of the iluid is accordingly decreased or increased.

While the coiled tubing 8 ordinarily will tend to maintain its adjustment or curvature setting by reason of the physical properties of the material of which it is formed,lit is preferable to employ self-locking worm gearing (4 and 5) in order accurately t0 make and maintain the desired adjustment.

In operation,the gaseous fluid enters through the arm II and flowing through the coils of the helixes I3 and' I4 is delivered to the mass Spectrometer or other device through arm I2. When any increase in the quantitative rate of flow is desired, the shaft I is rotated in a clockwise direction (viewed from the right of Fig. 1), loosening the helixes I3 and I4. When a decrease in the rate or quantity of ilow is sought, the shaft I is rotated in a counter-clockwise direction, tightening the helixes I3 and I 4.

Although in this illustrative embodiment, copper is given as the preferred material for the tubing, it is noted that any other material having the necessary flexibility and malleability may be employed. We have shown the tubing coiled into helixes, but the eifect is the same if the tubing is bent into a spiral or some other shape in which the radius of curvature of the bend and consequently the aperture through the tubing maybe varied.

In addition to providing a capillary leak embodying the novel concept of obstructing the fluid flow by Variably compressing a length of malleable tubing the present invention is significantly unique in the means disclosed for producing and controlling the requisite compression oi the tubing.

While reference has been made herein to a capillary-leak, tubing or passage, it is to be understood that operation of the device of this invention does not depend upon capillary action, and that the term "capillary is used for convenience to denote the aperture or passage size of the tubing through which gas or vapor is passed at a very low rate.

It will be apparent to those skilled in the art without departing from the principles oi the invention as disclosed herein, and for that reason it is not intended that it should be limited other than as may be required by the scope of the appended claims.

We claim:

1. In a device for regulating the flow of small amounts of fluid, the combination comprising a rotatable shaft, and a flexible tubing coiled about said shaft, said tubing having a portion connected with the shaft for rotation therewith, whereby the radius of curvature of the coil and passage size of the coiled tubing may be varied by rotation of the shaft.

2. In a device for regulating the ilow of small amounts of gas, the combination comprising a rotatable shaft, and a flexible tubing having a flattened portion coiled about said shaftI said tubing being connected to the shaft at one point forv corresponding rotation therewith, whereby the radius of curvature of the coil and Passage size of the coiled tubing may be increased or decreased by appropriate rotation of the shaft.

3. A device for regulating the flow of small A amounts of fluid including a coiled tubing of flexible malleable material having a capillary passage therein and means connected with said tubing for increasing and decreasing the radius of curvature of the coil to vary the passage size,

4. A device for regulating the passage of gas comprising a flexibled coiled tubing, and two members relatively rotatable with respect to each other, said coiled tubing having separate portions ilxed to each of said members whereby to increase or decrease the radius of curvature of the coil upon relative rotation of said members.

5. A device for regulating the passage of gas comprising a flexible coiled tubing of copper, a rotatable member, and a stationary member, said coiled tubing being fastened at spaced points to the rotary and stationary members respectively to increase or decrease in radius of curvature of the coil and passage size of the coiled tubing upon actuation of said rotatable member.

6. A device for regulating the flow of small amounts of gas to a closed system comprising a flexible tubing, a rotatable shaft, and a stationary member, said tubing being wound around said shaft and fastened at spaced portions to said shaft and said stationary member respectively, whereby to increase or decrease in radius of curvature oiI the wound portion of the tubing upon rotation of said shaft.

7. An adjustable capillary leak comprising a rotatable shaft, a stationary member, a flexible tubing wound around the shaft to form a helix, a portion of said tubing being fastened to said shaft for rotation therewith, and a portion of said tubing being fastened to said stationary member, and means for turning the shaft and setting the radius of curvature of the helix.

8. An adjustable capillary leak for controllingtwo fiat helixes extending in opposite directions f from a central portion, said central portion of said around the shaft to form two fiat heliXes extend- V ing in opposite directions from a central portion,

the central portion of said tubing being fastened to the shaft for rotation therewith and the opposite ends of the tubing being respectively secured to the frame, and self-locking worm gearing for turning the shaft to tighten or loosen the helixes of the tubing and for holding the tubing in a desired adjustment.

` 11.` An adjustable capillary leak comprising. a-

shaft, afiexible tubingfhaving a' flattened'intermediate portion wound around the shaftto form Number tubing being joined with the shaft for rotation therewith, a frame, saidy frame being composed of spaced members rotatably supporting said shaft and clamping members vsecuring the opposite ends of the tubing, and means for turning the shaft to vary the size of the inside passage formed in thef tubing.

ALFRED O. O. NIER. EDWARD P. NEY. MARK G. INGHRAM.

REFERENCES CITED The following references are of record in the file of this patent:

Umrno STATES PATENTS Name y Date 662,955 McClelland Dec. fi, 1900 1,416,603 'Brater e May 16, 1922 1,340,828 `Heap May 18, 1920 

